Science and Technology of Energetic Materials

Vol.63, No.5 (2002)

Research paper

Pulse laser ignition of a small amount of secondary explosive powder
Kouhei Murakami, Kazunari Inou, Motonao Nakahara, Shiro Kubota, and Kunihito Nagayama


Laser induced ignition of secondary high explosive charge will be one of the promising method of safe and reliable way of ignition of high explosives. The present method is based on the energy conversion from the pulsed laser energy to high pressure high temperature plasma generation by pulse laser ablation of thin metal layer adjacent to explosive. Method is also based on our findinge that very efficient energy conversion procese from optical to mechanical takes place by intentional roughening of the surface of a transparent medium through which laser beam propagates.
   Some of the unique feature of this study are as follows : (i) a very small amount of PETN of 3 to 15 mg is used, (ii) explosive thin layer is sandwitched in between the PMMA plates, whose thickness is almost 500µm, and (iii) the laser focused surface is intentionally roughened. Nd : YAG laser beam was focused through a PMMA plate of roughened surrace, which simulates experimentally the use of plastic optical filber. Initiation process was observed by the streak photography of the self - luminous wave front in PETN as well as the pulse laser shadowgraphy of the high - amplitude stress wave in PMMA medium induced by the detonation.

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